Traditional lime

techniques and practices

North India

1. Process starts immediately after calcination due to high reactivity of lime

2. Method Transportation and weather considerations

3. Storage in dry rooms in air tight bags

Process starts after calcination

Lime slaking techniques

1. Tank slaking2. Careful process3. Exothermic reaction4. Quick lime is mixed

with batches 5. Lime is added to water6. Mixing during slaking7. Enough supply of water8. Care and precautions

are required-protection of eye and skin

Lime slaking techniques1. Sieving after slaking- resultant milk

is allowed to flow through 3.35 mm IS sieve into the lower tank

2. Removing under burnt and over burnt lime stone

3. Storing lime putty in tanks for months, as per requirement

4. Months old lime putty for finishing works

5. A layer of water over the lime

Lime slaking techniques in Rajasthan1. Minimum of six months slaking

period2. Slaking with Jaggery in raw

form3. Adding salt during slaking4. Change of water everyday5. Adding Chach ( butter milk) to

the lime every alternate day

Lime slaking techniques

Mixing platform

Lime mortar storage tanks

Slaking tank

Lime putty storage tank

Quick lime storage area

Slaking tanks and lime putty storage tanksSize as per work requirement

Mixing platformsSize as per work requirement

Lime mortar storage tanks- direct protection from sun

Shades- direct protection from sun

Water supply

Lime slaking requirements

Lime mortarAggregates

1. Generally comprised of 65% of the volume

2. Several variations in ancient mortars

3. They act as filler4. Reducing the amount of

lime needed and thereby reducing drying shrinkage cracks

5. Gives a natural colour/ texture to the mortar.

6. Most important for analysis for ancient mortars

• River sand is the most common aggregates

• Pure quartz for finishing works

• Marble powder for finishing layers

• Red stone powders for matching colors

• Stone aggregates• Brick aggregates ( jeera)

Lime mortarAggregates

Well graded

Lime mortar

Requirements for AggregatesAggregates

Sharp (angular)

Lime mortar

Requirements for AggregatesAggregates

Lime mortarPozzolana

Surkhi1. Color is the representation of

the quality of Surkhi

2. Dark red color – Burning temperature as required for conservation works

3. Yellow color- Represents poorly burnt bricks with less reactive silicates and aluminates

4. It should be free from organic additives such as grass, coal, ash etc.

Lime mortarOrganic additives

1. To improve the properties of mortars both in fresh as well as hardened state

2. Improving workability/ plasticity

3. Providing initial and long term setting

4. Adding insecticide properties

5. Improving finishing in case of special works

6. Adding water proofing properties

7. Regional variations

1. Reduce shrinkage in lime works2. 25 mm to 100 mm long3. Added just before its use while knocking up

the lime mortar. 4. never added in advance as these are

weakened by prolonged contact with water and un-slaked lime.

Jute fibers and animal hairs

Jaggery

1. Used in dry form as well as wet form2. Add to lime mortar to improve water

proofing properties3. It makes the colors of the mortar little

darker4. In Rajasthan, it is added during the lime

slaking

1. Urad Dal (Split Black gram) lentil which 2. used for the lime concreting 3. finishing works to improve the workability

of the lime mortar. 4. Urab dal is grinded to a powder and then

soaked with water one night before its use. 5. The paste is then mixed with the lime

mortar in specified proportions.

1. Used in several forms such as buttermilk,curd and skimmed milk.

2. improve the binding and water proofingproperties.

3. used for decorative and polished works.4. Casein protein which is the chief ingredient

of the milk forms calcium

Pulses

Milk and milk products

Egg white

1. Egg white is churned with water for some time and then removed.

2. The left over clean egg water is added with lime putty for the final layer plastering works.

1. Improve the workability of the lime mortars for the decorative works

2. seeds are grounded to make a powder and soak in water overnight

3. mashed and sieved to remove fibers and other particles. The sieved water is mixed with lime mortar to add stickiness required for the profile plaster works.

Fenugreek Seeds

Fruit pulp

1. The pulp of belgiri fruit2. The fruit is dried in sunlight3. Soaked in water over night and then properly

meshed to separate the pulp of the fruit

Lime mortar

A buffalo pulls the stone wheel around the trench of a gharat in thecentre ,the masons names are included(top right),Dundlod (1888)

Mixing techniques Lime chakki

Mixing lime mortar

Lime mortarMixing techniques Lime chakki Stone grinding lime

mortar

Lime mortar

Source: Akbar- the AesthetePainting illustrated in Akbarnama depicts the construction of fort at Agra

Mixing lime mortar One of the labour is weighing the mortar and lime for checking the proportion of mix.

Mixing techniques- historical references

Source: Akbar- the AesthetePainting illustrated in Akbarnama depicts the construction of Fatehpur Sikri

Lime mortarMixing techniques- historical references

Crushing bricks Surkhi mixed with lime mortar

Sieving lime

Lime chakki

Lime mortarMixing techniques- current practices

1. Lime chakki is the most suitable way of preparing lime mortar

2. Thoroughly compressed or beaten

3. Action mobilizes the lime putty and spread over the surface of each grain

4. Storing lime mortar for long time under a layer of water

Lime mortarTraditional mixing techniques

The techniques of preparing lime mortar aredeveloped based on following threerequirements:

1. Filling the voids in between the sand grains withlime would develop the dense lime mortar fabric

2. Covering the sand particles surfaces with limeputty which developed well interlinked limemortar profile

3. Reducing the particle size of lime putty bycompressing over each which improves theplasticity and workability of the lime mortar

Lime mortarTraditional mixing techniques

1. Quantity of water2. Consistency of lime putty3. Gradual mixing4. Workability with

thorough mixing

5. Hand mixing is suitable when brick aggregates are used in lime mortar

1. Lime mortar is taken out before use

2. Ramming, beating , chopping and cutting

3. Water is not added4. Mixing organic additives just

before use5. Mixing surkhi before its use if

required

Lime mortarTraditional mixing techniques

1. Lime plastering is a porous layer of lime based mortars

2. Due to porosity of the lime mortar fabric, this layer acts as a sacrificial layer which provides a surface for accumulation of the salt components of the moisture which is trapped within the historic masonry.

3. Salt contents get deposited over the plaster surface during the evaporation process and therefore protect the chief building fabric

Lime plastering

Lime plastering

Number of LayersSingle coatDouble coatsThree coats

Type of masonry

Type of finishing

Type of form in case of stucco works

Work in layers allow each particle to carbonate

Plastering layers and textures

Plastering layers and textures

Lime plastering

Surface preparations

Coarse baseto provide keys in between different layers

BrushingCleaning

Algae, loose particles,dust etc

CuringThe surface should be wet before applying the plaster

layer. In case of dry surface, porous materials may absorb the water from the lime mortar leading to

early drying of fresh lime mortar and in result affecting the initial carbonation and hydraulic setting

Lime plastering

First layer- coarse aggregates- RoughAllowed to carbonate

Second layer with finer aggregatesSoft ramming for shrinkage cracks

Final layerHydraulic mortars for base coats

Lime plaster finishing layers

Matured lime putty, burnt clay, find sand and organic additives grinded together on stone grinder

Lime plastering

Wooden tools finishingNo use of steel tools for finishing

Spray curingTools for different types and sizes

for different kinds of works

Lime concreting

TerracingFlooringCopingFormsBase

works

Lime concreting

1. Lime mortar- Lime putty and sand

2. Brick aggregates of different sizes ( 1/8 inch to ½ inches)

3. Aggregates4. Jute fibers5. Urad Dal powder

Lime concreting

1. Laying2. Ramming/ compaction ( around

1 week)3. Beating ( approximately 3 weeks)4. Finishing with belgiri and Jaggery5. Sound check

Lime finishes

Lime Araish